SOMETIMES THE ENTIRE meaning of a movie winds up distilled into a single fleeting facial expression. In The Notorious Bettie Page, Gretchen Mol, playing the legendary pinup queen, gets no end of opportunities to emote on command; photographers are constantly requesting specific attitudes from their favorite model. "Show me saucy," one will say, whereupon Bettie will obligingly purse her lips, flare her nostrils, and shoot her eyebrows right up into the iconic curtain of bangs concealing her broad forehead. (The result doesn't suggest saucy so much as it does goosed.) But the expression that truly counts is one that steals across her face early in her new career, when a gaggle of male shutterbugs asks her to bend over and give them a better view of her ass--keister is the euphemism employed, actually, this being the early 1950s. Bettie hesitates for the merest instant, clearly unsure whether this would offend propriety . . . and then she grins. Not a salacious grin, but one paradoxically composed of equal parts innocence and naughtiness. It's a grin that says, Who am I to deny the world this wonderful keister?

Mol, God bless her, denies us absolutely nothing, getting joyously naked at the slightest provocation, or no provocation at all. ("You know, I could take this lil' ol' bathing-suit top off if you like.") But while Bettie isn't the least bit bashful about showing skin, the movie demonstrates remarkably little interest in getting underneath it. That's not a criticism. The Notorious Bettie Page is the second biopic directed by Mary Harron; like 1996's I Shot Andy Warhol, about wacko feminist Valerie Solanas, it opts to mythologize its subject rather than psychoanalyze her, an approach that's necessarily shallow but also enormously entertaining. There's a reason you're seeing this movie in April rather than during the annual fall Oscar-bait onslaught. Even the black-and-white cinematography, mimicking the seedy atmosphere of Samuel Fuller's pulp classics of the era, comes across as playful rather than reverential.

It's not that Harron and her cowriter, Guinevere Turner, haven't thoroughly researched Page's life. They simply aren't interested in using the details as psychological shorthand. You can sense their impatience as they barrel through obligatory childhood anecdotes and dispense with Bettie's first marriage in three rapid-fire scenes: Two minutes after he slips the ring onto her finger, she's packing her bags to leave. Weirder still, the film subtly but unmistakably implies that Bettie's father sexually abused her, and it later shows her being gang-raped, but then never alludes to either incident again. In your standard great-man (or great-woman) biopic, we'd be subjected to multiple flashbacks and teary incriminations and/or confessions; here, there's absolutely no suggestion that Bettie's eventual participation in bondage porn was inspired by early trauma. The information is dutifully presented, then boldly ignored, as if Harron and Turner included it only for fear of being charged with sweeping it under the rug.

In a way, this approach to the biopic is an act of humility. Harron understands that it's impossible to make sense of a real human being within the context of a feature-length film, so she doesn't even try. Instead, she uses the "character" of Bettie Page to express an idea--basically, a retelling of the Fall of Man, with Bettie as Eve and a Senate subcommittee as the serpent. Despite her fervent Christian beliefs, Bettie sees nothing sinful about posing naked or pretending to wield whips and chains; for her, it's all fun and games. Only when she's hauled before experts who testify that consumption of pornography inevitably leads to "suicide, murder, and psychosis" does she abruptly decide to button up. This caricature of sensual naivete probably bears about as much resemblance to the real Bettie Page as it does to Betty Rubble, but there's something poignant and--for certain sensibilities--intensely erotic about such goggle-eyed enthusiasm in the midst of depravity, whether it's credible or not.

What's amazing, really, is just how credible it seems. Because her performance is largely opaque and slightly cartoonish--Johnny Depp as Ed Wood is the closest analogue I can think of--Gretchen Mol isn't likely to get any awards traction for her work here. Nor would I make any great claims for her generally. (Indeed, Bettie's bad acting in various auditions and class exercises bears a pronounced resemblance to Mol's irritatingly earnest turn as Matt Damon's nag of a girlfriend in Rounders.) Yet I can't think of another actress who could have pulled off the odd, beguiling mix of sacred and profane that Mol achieves here. At one point, while shooting a tawdry little short called Sally's Punishment, Bettie shoves her captive, bound and gagged, into the trunk of a car. Doing her very best impression of a dominatrix, she stands there in her leather corset and makes angry half-pointing, half-stabbing motions with her index finger . . . and then proceeds to close the trunk so gently that you'd think it was filled with nitroglycerin. Philip Seymour Hoffman had Capote's lisp down perfectly; Joaquin Phoenix held Cash's guitar in just the right spot. But that blatantly phony trunk slam? That I believed.